High-vacuum pump



April 22, 1924..

W. GAEDE HIGH VACUUM PUMPl Filed Sept. 22. 1922 4 goe/fwff@ PATENT OFFIC WOLFGANG GAEDE, 0F KBLSRUEE, GERMANY.

HIGH-VACUUM PUMP.

Application led September 22, 1922. Serial No. 589,78.

Tol all whom t may concer/n.'

- A Be it known that ll, Dr. 1WOLFGANG GAEDE,

a citizen of Germany, residing at-vlarlsruhe, in the State of Baden, Germany, have invented certain new and useful improvements in High-Vacuum Pumps; and I' do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to improvements in high vacuum pumps, and more particularly in pumps of the type in which a jet of a suitable vapor such as mercury vapor is l made to flow across an opening through which there is communication from the chamber to be evacuated,the gas or air'being carried away by the jet to a condensing chamber, and the mercury vapor which gets into the chamber to be evacuated being condensed and removed from said chamber. One of the objects of the improvements is to provide a pump of this type in which the requisite pressure of the vapor is relatively low. lVith this object in View means are provided for condensing the mercury vapor immediately after passing across the said opening, for which purpose l cause the said jet to flow after passing across the opening through a cooled metallic tubular member the internal diameter of which is substantially the same as that of the nozzle through which the jet of mercury is discharged. Thus the mercury vapor is brought in intimate Contact with an efectively cooled surface; Another object of the improvements is to provide a pump in which a plurality of sectional pumps all connected to the same vapor supply are arrangedin series, the chamber upon which an earlier sectional pump of the series exerts its evacuating eifect being the condensing chamber of the next succeeding sectional pump. Thereby the vacuum attained is of progressively increasing value, from the first sectional pumpof the series to that directly connected with the chamber to be evacuated. Other objects of the improvements will appear from the following description of the pump.

ln order that my invention be more clear- I ly understood an example embodying the same has been shown in the accompanying drawing, in which- Fig- 1, is a diagrammatical sectional view showing a nozzle constructed according to my invention, and

Fig. 2, is a vertical section showing the improved apparatus.

Referring at first to the view shown in F ig. l, the suction member proper consists of a nozzle a from which a jet of mercury vapor may be impelled and directed down- `wardly, and a metallic member b having an axial bore c in alignment with the nozzle a spaced at an interval from nozzle a and cony stituting with the nozzle a. vapor ejector. The member b is fitted within a water jacketed cylinder d so as to be in thorough cooling Acontact therewith. I have found that an exceedingly eifective cooling is insured by discharging the` jet of mercury vapor through a cooled metallic body having a passage o of a diameter substantially equal to that of the rim of the nozzle. Said metallic body b is in good heat transmitting contact with the jacket d by forming the body with a comparatively narrow flan e e and filling the annular channel f forme by and between the main part of themember and the wall of the cylinder with liquid mercury, insuring a thorough transmission of heat. Preferably the mercury is supplied by condensation in thev chamber above the member b. An important feature of this construction resides in that the member ZJ can readily be withdrawn from the cylcooling member where it is immediately` cooled. As long as the air pressure within the chamber above the member b exceeds that of the jet of vapor passing into the bore o the air is drawn by suction through the narrow space between the Yrim of nozzle a and the `adjacent rim of member b and into the jet of vapor and carried along by the said jet, the pump having the function of an 'ordinaryejeeton If after some time the pressure of the air within the chamber to be evacuated has been reduced until it is equal to or smaller than the pressure of the vapor passing across the annular slot between the nozzle a and the' core c, the air can not be drawn into the jet by suction, a How of a fluid from a space of lower pressure into a space of higher pressure being impossible. Nevertheless air continues vto be carried.,

along, now by diffusion, and the pump has the function of a diiusion pump.

By constructing the o erative parts of the pump so as to be readily removed theresey g; meagre i vaporizing chamber h formed within a cylindrical casing the lower portion 1 of which 1s formed with ay thick wall and has a closed bottom, and the upper part of which has a thin wall 2 provided at its top with a -ange 3. In the operation of the pump the chamber is filled about to a level indicated by a dotted li-ne 4 with mercury. On the shoulder formed at the top of the thick wall 1 a partition 10 is supported through the intermedlary of a conical ring or seat 11. The upper surface of partition 10 inclines funnelwise to an eccentrically placed bore which extends vertically throu h the partition. Into this bore telescopica'lly arrangedv pipes 5 and 6 are fitted which extend downwardly therefrom and to a point near the bottom of the casing 1, where they are connected to a plug 9 having an axial bore. The space between the pipes 5 and 6 is closed both below and above, and constitutes a heatinsulating air space in the double wall so dividing the spacey within the bore of pipe 5 and the chamber h. Into the inner pipe 5 there eX- tends downwardly from abc ve a coolingrod 7 made from iron or another suitable metal. The pipe 5 is provided for allowing the condensed mercury to flow back into the casing 1,' which mercury is normally at a level within pipe 5 indicated by the character 8. Reevaporization of the mercury within ipe 5 isl prevented by the heat-insulating wa l 5, 6 and the heat-absorbing iron rod 7.

In an axial bore through the partition 10 a pipe 12 is secured. It extends downwardly and into the casipg 1 and upwardly into the upper parts of the pump. The said pipe serves to carry the vaporized mercury upwardly and to the different operative parts of the pump, as will presently be described. The pipe 12 is disposed within a pipe 13 fitted in the said axial bore through the partitionlO and insulating the pipe 12, for preventing condensation of the mercury vapor therein. Further, the pipe 13 is used for returningA condensed mercury into the casing 1'. Preferably the pipe 12 is provided at its lower end with a hood 14 preventing the condensed mercury falling from the pipe 13 from being carried along by the rising mercury vapor. The drops of condensed mercury fall from the hood 14 at pomts remote from kthe current of mercury vapor flowing into the pipe 12. The pipe 12 l is providedl with holes 15, 16, and 17 through which it communicates with the nozzles of the sectional pumps, as will be described hereafter.

From the flange 3 a cylinder 20 rises which is Surrounded by-a jacket 21, and through the annular chamber provided betweenthe cylinder 2O and the jacket 21 a. cooling medium such as water is circulated which is supplied thereto and withdrawn therefrom through nip les 22 and 23. Vithin the said annular ciamber a pi e 24 is located which communicates with t e cylinder 20 at a point near the bottom thereof and which is connected at its top end with aflnipple 25 adapted to be connected with a. suction pump for producing a vacuum within the pipe 24 and the part of the c linder immediately connected therewith. T e pipe 24 is also in communication with an annular chamber 26 which will be described hereinafter. Substantially at the height of the flange which carries cylinder 20 and below the bottom end of the ipe 24 a cooling body 18 is fitted in the cylinder 20. Tight engagement with the cylinder is afforded by a leather cup 19. At intervals above body 18 and within cylinder 2O similar cooling bodies 27, 28, and 29 are arranged, each similarly' provided with a leather cup 19. The upper surface of the body 18 inclines funnel- Wise to a vertically extending eccentrically situated bore, and in this bore the rod 7 already mentioned is carried. The rod extends vertically downward through chamber i and its lower end extends as has been said within pi e 5. The rod 7 is in its upper part provided with a bore 33 which leads from the chamber lo above and opens below to the chamber z'.

- Above the leather cups 19 the bodies 27, 28, and 29 are reduced in diameter, and in the operation of the pump the annular channels thus provided between the bodies and the wall of the cylinder are filled with mercury, providing effective heat transmissior` from the bodies to the cooled wall of the cylinder 20.

The pipe 13 carries hollow members 3() and 35 held in position by pipes 34 and communicating with the inner pipe 12 through the openings 15 and 16 respectively. The member 30 carries a nozzle 31 discharging into a bore 32 eccentrically placed and vertically extending through the cooled body 27. In a similar Way the member 35 is equipped with a nozzle 36 discharging into a bore of the cooled body 28. The up er surfaces of bodies 27 and 28 are conica ly sha ed and slope downwardly from the points w ere the. bores just mentioned are drilled. Through the bodies 27 and 28 opposite the bores just mentioned and near the lower rims of the conical upper surfaces are drilled ali ed and vertically extending bores. In the ore in the upper body 28 a pipe 37 is secured through which the mercury condensed in the chamber n above, overflowing from the annular channels mentioned above, flows down# wardly and into the next chamber m. The body 27' carries a similar pipe 38 conducting condensed mercury into the next lower chamber Ic, from which it flows through 33 and through an opening 51 formed throu h the lower ,pipe section 34 and through t e annular passage aEorded between the'pipes 34 and 13 into the casing 1.

To the top ends of the pipes 12 and 13 members 39 and 40 are secured. The member 39 is formed with an axial recess `having a conical side wall, and the member 40 is formed ,with a conical outer face. rllhe members 39 and 40 are so placed one within the other as to' rovide an annular outwardly flaring nozz e for the mercury vapor coming from the top end of pipe 12, the relative distance of the walls at the narrowest part of the passage' of the nozzle being about .1 or .15 millimeters, A,Below the said annular nozzle a fourth nozzle is provided by a body 43 formed with an annular chamber 42 communicatin through the holes 17 with the pipe 12, said chamber discharging downwards through a narrow annular passage 52 provided betweenv the body 43 and the outer wall of the pipe 13i The major part of the said nozzle, and more particularly itsy tip 41, projects into a funnel shaped axlal opening through thev cooling ring-r 29, .and discharges through a ringshaped orice formed between body 29 and pipe 13 and into the condensing chamber n, which chamber encloses the nozzle 36. The parts 29 and 43 may be dispensed with.

The member 39 carries a disk 53 formed with a hole 45 and acted upon by a spring 444 forcing all the nozzles and the pipes carrying the'same downwardly and on the annulary seat 11. To the ltop of the cylinder 20 a high vacuum pipe 46 having a flange 47 is secured, which pipe is made tight by a packing ring 48 of -leather ortho like. At`

its. lower end that pipe 46 extends beyond flange 47 and is there l provided with a flange 49 tightly tting in the cylinder 20.

Above the flange 49 and between the lower part of the pipe 46 andthe upper part of the cylinder 20 the annular chamber 26 is formed which is partly Iilled V`through a hole normally closed by a screw 50 with mercury constituting a tight closure of the low vacuum chamber 26 as against the high vacuum chamber 46.

ln the operation of the pump the mercury confined within the receptacle 1 is heated and a low vacuum pump connected to the nipple 25 is set in operation. The mercury vapor rises from the receptacle 1 through the pipe 12 and to the individual nozz es connected therewith. Thel va or flowing through the hole 15 and into t e chamber 30 rushes through the nozzle 31 and into the Acooled bore 32, and it evacuates the chamber m situated between the bodies 27 andp28. The condensed mercury falls on the cup shaped cooling body 18 from which a .part flows throughthe axial bore 33 of the cooling rod 7 to chamber z' and thence through pipe 5 into the chamber h of the receptacle 1. The remaining part flows throu h the hole 51 and the annular passage ormed between the pipes 34 and 13 to chamber z'. Simultaneously, a portion of the vapor which rises in pipe 12 Hows through the hole 16 into the chamber 35, from which it rushes through the nozzle 36 into the cooled bo're of the body 28, thus evacuating the chamber arranged aboveland between the bodies, 28 and 29. The condensed mercury collectin in and overflowing from the annular c annel which surrounds body 217 flows through the pipe 38 into the chamber c, mingling there with the mercury condensed from the jet from nozzle 31, whose course has already been described. In a similar Way other portions of the mercury vapor which rises in pipe 12 flow throu h the' nozzles provided res ectively by t e bodies 43 and 39, 40. vapor which condenses inchambers 30, 35, 42, and the chamber formed within member 39 will be returned by pipe 13 to chamber L.

lt will be perceived that the succession of chambers la, m, n, etc. arranged as described, with evacuation nozzles directed into the passageways which open from nyV chamber to chamber, constitutes apparatus I by which in a succession of steps air may be exhausted from the ultimate chamber, the

`chamber communicating with pipe 46. The

degree of attenuation so achieved is very high indeed. Each of the lower chambers constitutes a preliminary vacuum chamber for the chamber located next above. 'lhe pressure attained within the successive chambers is gradually reduced from thev lowermost to the uppermost chamber, and in the pipe 46 a vacuum is produced, attenuated to a degree which can not be measured by known apparatus.

The heat 1s ed'eotively transmitted from the bodies 18, 27, 28, and 29 through the yco I claim:

1. In a vacuum pump a vertically standing elongate casing with heat-absorbing walls, a partition of heat-conducting material extending horizontally within the casing, the seam` of union between casing wall and partition being sealed with a body of heat-conducting liquid, said par' tition being provided with a vertically extending passageway, a nozzle arranged at -an interval above said partition and directed into said passageway, Aand means for projecting a jet of condensable vapor from said nozzle, across the interval, and into said passageway.-

2. In a vacuum pump, the combination, with a vertically standing metallic casing, a metallic partition arranged within said casing and at its periphery forming together with the casing a horizontally disposed annular channel, said partition dividing the casing into two chambers one adapted for connection with a container to be evacuated and the other one adapted to be connected with a vacuum producing apparatus, said partition being formed with apassage connecting said chambers, and a body of mer- Acury Within said channel, of a nozzle discharging into said passage from the side of the container to be evacuated, and arranged at an interval from said partition, and means to produce a jet of vapor through said nozzle and passage.

3. In a vacuum apparatus, the combination of a plurality of pumps each comprising a chamber to be evacuated and a condensing chamber, a passage between the said chambers and means to produce a jet or" condensable vapor through said passage and into the condensing chamber, the vacuum chamber of one of said pumps constituting the condensing chamber of another one, the 'et-producing means for the several pumps eing connected to common vapor producing means.

4. In a vacuum pump a vertically standing elongate casing with lfeat absorbing walls, two partitions of heat-conducting material extending horizontally within the casing and both Apenetrated by vertically eX- tending bores, the lower partition forming with the inner wall of the casing a peripheral channel, and its upper surface being conical, the bore which penetrates said lower partition extending from theV apex of said cone, and means for projecting through both bores jets of condensable vapor. l

5.' In a vacuum pump a vertically stand-l ing elongate casing with heat absorbing walls and divided internally by three horizontally extending perforate partitions of heat-conducting material, the middle partition of the three forming with the inner wall of the casing a peripheral channel, its upper surface comcal, the perforation which extends through it extending from the apex of the cone, means for directing through each perforation a jet of condensable vapor, the middle partition being further provided with an additional bore extending vertically through it at a point remote from the apex of the cone.

6. In a vacuum apparatus, the combination, with a vertical metallic cylinder, and cooling means therefor, of metallic partitions itted in said cylinder and forming with the chamber Walls peripheral channels, said partitions being formed with passages and spaced at intervals from said partitions, nozzles opening into said passages, means to produce a vacuum below the lowermcst partition, means to cause jets. of mercury vapor through said nozzles and passages,

and means arranged at levels higher than the annular channels which surround said partitions for withdrawing condensed mercury from said chambers.

7. In a vacuum pump, the combination, with a casing comprising a chamber to be evacuated, a condensing chamber, and a chamber for vaporizing mercury, said chamber to be evacuated and condensing chamber communicating with each other through a passage, and means arranged within the vaporizing chamber to cause a jet of mercury through said passage in a direction from the chamber to be evacuated to the condensing chamber, a pipe connecting said condensing chamber and vaporizing chamber and immersed into the mercury confined Within the vaporizing chamber for returning condensed mercury from the condensing chamber into the vaporizing chamber, and a heat-insulating jacket surrounding said 1 e. P In a vacuum pump, the combination, w'thv a casing compris-ing a chamber -to be evacuated, a condensing chamber, and a chamber for vaporizing mercury, said chamber to be evacuated and condensing chamber communicating with each other through a passage, of means arranged within the vaporizing chamber to project aj et ot mercury through said passage in ra direction from the chamber to be evacuated to the condensing chamber, a pipe connect-ing said condensing chamber and vaporizing chamber and immersed in the mercury confined within the vaporizing chamber for returning condensed mercury from the condensin chamber into the vaporizing chamber, an a hea-ti conducting rod projecting into said pipe, said rod being provided with a passage oonnected with the condensing chamber for conducting condensed mercury therefrom.

` 9. In a vacuum pump, the combination, with a cylinder divided y a partition internall into a chamber to be evacuated and a con ensing chamber, said partition fittingl with a passage, a. vaporizing chamber, a plpe passing through said partitions and communicating iviththe vaporizing chamber, a nozzle connected with said pipe and opening into said passage through the partition for blowing therethrough a jet of vapor from the vaporizing chamber, and means to evacuate said condensing chamber.

l0. In a vacuum pump, the combination, with a casing having a chamber to be evacuated and a condensing chamber communicatingtherewith through a passage, of means to cause a jet of mercury vapor through said passage in a direction from the chamber to be evacuated to the condensing chamber, a pipe connected with said chamber to be evacuated, the joint of said-pipe and casing including a liquid-sealed vacuum chamber, and means tocause a vacuum in said condensing chamber and vacuum chamber.

1l. 1n a vacuum pump, the combination, with a cylinder having a chamber to be evacuated, a condensing chamber, a.vaporiz ing chamber, and partitions separating said chambers, said chamber to be evacuated and condensing chamber communica-ting with each other through a passage, of telescopically arranged pipes passing from the vaporizing chamber to the chamber to be evacuated, and a nozzle opening into said passage and connected'wit-h the inner one of said telescoping pipes for supplying vapor from the vaporizing chamber thereto, the outer one of the telescoping pipes being open to the part connecting the nozzle and inner pipe for gathering condensed mercury and returning the same to the vaporizing chamber.

12. In a vacuum pump, the combination, with a cylinder having a chamber to be evacuated, a condensing chamber, a vaporing chamber, and partitions separating said chambers, said chamber to be evacuated and condensing chamber communicating -with each other through a passage, of telescopically arranged pipes passing from the vaporizing chamber to the chamber to be evacuated, the inner one of said pipes being laterally enlarged atthe end projecting into the vaporizing chamber, and a nozzle opening into said passage and connected with the inner one of said telescopically arranged pipes for supplying vapor from the Vaporizing chamber thereto, the outer 011e of the telescoping pipes being open to the part connecting the nozzle and inner pipe for gat-h ering condensed mercury and returnlng the same to the vaporizing chamber. v

13. In a vacuum pump, the combination, with a cylinder having a. chamber to be evacuated, a condensing chamber, and a Vaporizing chamber, partitions separating said'chambers borne upon a common stem and removably mounted within said cylinder, and means connect-ed with the partition intermediate said chamber' to be evacuated and condensing chamber for producing a jet of vapor communicating with the chamber to be evacuated and into said condensing chamber, a spring acting on said partition, structure f'or holding the same in place Within the cylinder, and means for closing said casing and providing a rea-r support for said spring.

In testimony whereof I hereunto afiix my signature in the presence of two Witnesses.

DR. WOLFGANG GAEDE.

Witnesses:

FRANK H. REDIKER, HANNAH Genom. 

